1. Technical Field of the Invention
The present invention relates generally to control apparatus for electric generators and electric power generation systems.
More particularly, the invention relates to a control apparatus which controls power generation of an automotive alternator, communicates with a vehicle ECU (Electronic Control Unit), and has a function of detecting an initialization state of the control apparatus.
2. Description of the Related Art
A conventional control apparatus for an automotive alternator is configured to communicate with a vehicle ECU and control power generation of the alternator according to command signals transmitted from the vehicle ECU. For example, DE19638872 discloses such a control apparatus.
More specifically, the vehicle ECU transmits the command signals to the control apparatus at predetermined time intervals. Each of the command signals indicates target values of power generation control parameters, such as a target output voltage of the alternator and a target time period of gradual excitation for the alternator. Upon receiving each of the command signals, the control apparatus controls power generation of the alternator using the target values of the power generation control parameters indicated by the command signal.
Further, the control apparatus includes a memory to hold therein the target values of the power generation control parameters, which are indicated by a last-received one of the command signals, until receiving a next one of the command signals. Thus, with the memory, the control apparatus can control the alternator according to the last-received command signal until receiving the next command signal.
Furthermore, the control apparatus is electrically connected to an output terminal of the alternator, so as to be supplied with electric power necessary for operation. The output terminal of the alternator is also electrically connected to electrical loads and an automotive battery.
When the output voltage of the alternator temporarily drops below a predetermined level, for example, due to a cranking operation of an engine starter driven by the alternator or an increase in the electrical loads of the alternator, the control apparatus performs a restart operation that causes it to enter an initialization state.
In the initialization state, the memory of the control apparatus is initialized so that all the target values of the power generation control parameters stored in the memory are overwritten with corresponding default values.
Consequently, it becomes impossible for the control apparatus to control the alternator according to the last-received command signal. In other words, it becomes impossible for the control apparatus to control the alternator as commanded by the vehicle ECU.